title: Unbalanced atrioventricular septal defect: definition and decision making.
abstract: Unbalanced atrioventricular septal defect is an uncommon lesion with widely varying anatomic manifestations. When unbalance is severe, diagnosis and treatment is straightforward, directed toward single-ventricle palliation. Milder forms, however, pose a challenge to current diagnostic and therapeutic approaches. The transition from anatomies that are capable of sustaining biventricular physiology to those that cannot is obscure, resulting in uneven application of surgical strategy and excess mortality. Imprecise assessments of ventricular competence have dominated clinical decision making in this regard. Malalignment of the atrioventricular junction and its attendant derangement of inflow physiology is a critical factor in determining the feasibility of biventricular repair in the setting of unbalanced atrioventricular septal defect. The atrioventricular valve index accurately identifies unbalanced atrioventricular septal defect and also brings into focus a zone of transition from anatomies that can support a biventricular end state and those that cannot.
authors.affiliation: Division of Pediatric Cardiac Surgery, The Children's Heart Clinic, Children's Hospitals and Clinics of Minnesota, MN, USA.
authors.forename: David M
authors.initials: DM
authors.lastname: Overman
authors.forename: Jeanne M
authors.initials: JM
authors.lastname: Baffa
authors.forename: Meryl S
authors.initials: MS
authors.lastname: Cohen
authors.forename: Luc
authors.initials: L
authors.lastname: Mertens
authors.forename: David B
authors.initials: DB
authors.lastname: Gremmels
authors.forename: Anusha
authors.initials: A
authors.lastname: Jegatheeswaran
authors.forename: Brian W
authors.initials: BW
authors.lastname: McCrindle
authors.forename: Eugene H
authors.initials: EH
authors.lastname: Blackstone
authors.forename: Victor O
authors.initials: VO
authors.lastname: Morell
authors.forename: Christopher
authors.initials: C
authors.lastname: Caldarone
authors.forename: William G
authors.initials: WG
authors.lastname: Williams
authors.forename: Christian
authors.initials: C
authors.lastname: Pizarro
keywords: CHD–univentricular heart; atrioventricular septal defect; echocardiography; outcomes